In U.S. Pat. No. 4,161,656 it is noted that the index-modifying dopants, used to grade the index profile of an optical fiber, fluoresce when exposed to ultraviolet radiation. This phenomenon is then employed as a means for measuring the index profile of fibers and fiber preforms.
There are numerous areas of activity that employ uv radiation in which the intensity and distribution of the uv light are important parameters. These include, for example, industrial monitoring of materials and processes, spectrofluorescent studies of materials, photoresist illumination, solar simulation, semiconductor annealing, computer PROM erasing, and germicidal sterilization.
Some of these processes are conducted in hostile environments and at wavelengths for which there are no satisfactory detectors. In many of these applications, the area of exposure is very small, making it very difficult, if not impossible, to measure the distribution of the uv light over the area. What is required for such measurements is a sensitive, yet extremely small uv sensor.